Piston



1,634 151 June 1927 .1. D. LANNON ET AL PISTON Filed April 19, 1923 ad i lllllllllluhllfll I Patentea'June 28, 1927.

UNITED STATES 1,634,151 PATENT OFFICE.

JOHN D. LANNON AND RALFH R. TODD, OF PONTIAC, MICHIGAN, ASSIG-NORS TO GEN ERAL MOTORS CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELA- wean Application filed April 19, 1923. Serial No. 638,218. v I

This invention relates to pistons and is illustrated as embodied in an aluminum piston for an automobile engine.

Pistons of aluminum, or an aluminum al- 6 y, have a high coefiicient of expansiomand if they accurately fit their cylinders when hot, there is an excessive learance after they cool. An object of this i vention is to limit the excessive contraction of such a piston, 10 as for example by the use of an internal bracmg expansion.

From this point of view the invention contemplates limiting the contraction of a pis- '15 ton by an internal bracing member having a lower coefficient of expansion, and preferably in the form of an annular brace or ring. In one form, the skirt of the piston is expansible and contractable, as for example by being separated into relatively movable sections, and the excessive contraction is ofiset by wedging the skirt of the piston ra dially, that is to say by spreading the sec; -tions apart. While not necessarily so limited, the inventionfrom this point of view is especially adapted for embodiment in aluminum pistons having skirts provided ith heightwise slots.

Other features of the invention relate to the manner of supporting the bracing device, and to a novel annular brace or ring shown as having adjustably connected ends, and to various other novel combinations and desirable particular constructions of parts which will be apparent from the following description of several illustrative embodiments of the invention shown in the accompanying drawings, in which:

Figure 1 is a vertical section through one form of slotted aluminum piston having a steel annular bracing ring seated in a groove formed internally of its skirt portion;

Figure 2 is a view of a modified form, corresponding to the lower part of Figure 1, but showing the use of a different form of bracing member;

Figure 3' is a view corresponding to Figure 2 showing a second modified form in which the ends of the bracing member are m connected;

Figure 4: is a bettomplan view looking in the direction of the arrows H inFignre l, but showing a third modified form of the in vention;

Figure 5 is a bottom planview of a novel member having a lower coefficient of bracing ring which may be used instead of the rings shown in Figures 1 to 4; and

Figure 6 is a view corresponding to Figure 5 but showing a different form of bracing ring.

As explained above, this invention is especially well adapted for embodiment in pistons such as the one shown at 10 in the drawings, which are made of aluminum or an aluminumalloy, and which are provided with one or more heightwise slots 12, which may or may not connect with horizontal slots 14 in such a manner as to provide resiliently connected sections which are capable of being spread apart. The internal surface of the skirt of the piston is provided with brace-supporting means such as the grooved flange 16 (Figure 1), or the forked lugs 18 (Figure 4), or a groove formed directly in the piston wall (Figure 3). In the modification shown in Figures 1 and 4 a split ring 20, which is made of material having a lower coefiicient of expansion than the piston, is seated in the grooved flange 16 or in the forked lugs 18, preferably in such a manner as to bridge the slot or slots 12, so that when the piston cools it will resist the excessive contraction explained above by wedging the piston walls radially, i. e. by spreading the sides-of the slot or slots l2 apart I prefer thati this bracing ringbe made ofspring .stee

In the embodiment shown in Figures 1 and 4, the bracing ring is round in cross sec tion, and the ends are not connected, so that thering resists the contraction of the piston by a spring action. In the embodiment shown in Figure 2, the bracing ring 22 is square in cross section. In the embodiment shown in Figure 3' the bracing ring 24 is roundin cross section, and its ends are bent at right angles to the plane of the ring and are connected by a plate 26 which is held 111 place by a head 28 on one. end of-the ring and which is formed with a slot 30 embracing the other end of the ring. The plate 26 limits expansion of the ring, and the slot'30 may, if desired, be so proportioned as also to limit contraction of the ring to a desired maximum; The ring 32 shown in Figure '5 has one side flattened to bring its ends 34 into alinement with one another and out of engagement with the piston wall, and these ends are adjustably connected by a turn-- buckle device 36 pinched into an annular groove 38 in one end of the ring and threaded on the opposite end of the ring. The ring 40 shown in Figure 6 has its ends connected by a similar turnbuckle device 36 but is polygonal in form, t

In the operation of all of the described embodiments of the invention, excessive contraction of the piston is prevented by the limiting action of one of the various forms of bracing members which, being of steel or equivalent material, contract very much less than the aluminum of the piston.

While several illustrative embodiments of our invention have been described in detail,

or otherwise than pended claims.

We claim:

- 1. A split bracing ring for a piston having a turnbuckle device adjustably connecting its ends.

2. A split bracing ring for a piston having one side flattened to bring its ends into alinement with one another, and a turnbuckle device adjustably connecting said ends.

In testimony whereof we aflix our signatures.

J. n. LANNQN. R. R. TODD.

by the terms of the ap- 

